US20080011943A1 - Optical system and method for monitoring variable in rotating member - Google Patents

Optical system and method for monitoring variable in rotating member Download PDF

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Publication number
US20080011943A1
US20080011943A1 US10/551,060 US55106003A US2008011943A1 US 20080011943 A1 US20080011943 A1 US 20080011943A1 US 55106003 A US55106003 A US 55106003A US 2008011943 A1 US2008011943 A1 US 2008011943A1
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United States
Prior art keywords
optical
source
energy
lens
optical energy
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Abandoned
Application number
US10/551,060
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English (en)
Inventor
Pieter Lodewikus Swart
Ludi Kruger
Anatoli Aleksandrovich Chtcherbakov
Albertus Japie Van Wyk
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University of Johannesburg
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University of Johannesburg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
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Assigned to UNIVERSITY OF JOHANNESBURG reassignment UNIVERSITY OF JOHANNESBURG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KRUGER, LUDI, SWART, PIETER LODEWIKUS, VAN WYK, ALBERTUS JAPIE, CHTCHERBAKOV, ANATOLI ALEKSANDROVICH
Publication of US20080011943A1 publication Critical patent/US20080011943A1/en
Abandoned legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/80—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water
    • H04B10/801—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water using optical interconnects, e.g. light coupled isolators, circuit board interconnections

Definitions

  • This invention relates to a system and method utilizing optical means to measure or monitor variables relating to a rotating member, in use.
  • SAWs surface acoustic waves
  • Another known system and method measure torsion from a considerable distance from the member by magnetically programming the member and using proprietary circuitry and signal conditioning.
  • the system measures the modifications of the magnetic field generated by the shaft torsion when torque is applied.
  • An important disadvantage of this system is that the member has to be made of a ferromagnetic material with a memory of magnetization.
  • a system for monitoring a variable relating to a rotating member comprising:
  • the variable may be any one or more of strain, speed of rotation, temperature at or near the member, torque applied to the member, torsion in the member, bending moment, stress, pressure etc.
  • the optical source may be mounted on a stationary platform and may comprise a broadband optical source such as a super-luminescent diode or a frequency sweeping narrowband source, coupled to a first length of optical fibre.
  • a broadband optical source such as a super-luminescent diode or a frequency sweeping narrowband source
  • the optical transmission system may comprise a first lens and a second lens, the first lens being mountable on the stationary platform in substantial alignment with the second lens which is mountable on the member.
  • the first and second lenses may comprise a pair of graded-index (GRIN) lenses.
  • the transducer may comprise a second length of optical fibre and optical energy modulating means connected to the second length of optical fibre.
  • the modulating means may comprise a first optical energy reflective element and a spaced second optical energy reflective element.
  • the first and second elements may comprise a first and a second Bragg grating having in wavelength spaced first and second center wavelengths respectively.
  • the modulating means may change the phase of an interferometric signal, or the amplitude of the optical signal.
  • the first and second gratings may be mounted on the member in spaced relationship relative to one another and in other embodiments in at least partially overlapping relationship relative to one another.
  • the gratings may be mounted at ninety degrees relative to one another.
  • the first and second gratings are mounted on the rotating member at forty-five degrees on either side of a longitudinal axis of the member.
  • Means for separating optical energy propagating away from the source and reflected energy propagating in an opposite direction from the transducer may be provided in the first length of fibre.
  • the separating means may comprise an optical circulator having a first port connected to the source, a second port connected to the first lens and an output.
  • the output of the circulator may be connected to means sensitive to modulation of the optical energy.
  • Said means may comprise means sensitive to the modulation in the optical domain, alternatively it may comprise a suitable converter and means sensitive to resulting electrical signals.
  • the invention further includes within its scope a method of monitoring a variable relating to a rotating member, the method comprising the steps of:
  • FIG. 1 is a block diagram of an optical non-contact system according to the invention for monitoring a variable relating to a rotating member
  • FIG. 2( a ) is a diagrammatic representation of a first embodiment of the system with a transducer of the system mounted on a rotary shaft;
  • FIG. 2( b ) is a similar diagrammatic representation of a second embodiment of the system
  • FIG. 3 is a typical spectrum diagram of wavelength separation measured with the system according to the invention and in accordance with the method according to the invention;
  • FIG. 4 is a spectrum diagram generated in accordance with the method of the invention and illustrating changes in wavelength separation for three different values of torque applied to the shaft;
  • FIG. 5 is a graph illustrating a comparison between theoretical calculated values and measured values of change in wavelength separation against torque.
  • a system according to the invention for monitoring in a non-contact arrangement certain variables relating to a rotating member in use is generally designated by the reference numeral 10 in FIGS. 1 and 2 .
  • the rotating member may for example be an elongate shaft 12 mounted for rotation about a longitudinal axis 14 thereof.
  • the system comprises an optical source 16 mounted on stationary platform 18 supporting a measuring station.
  • the optical source 16 may comprise a broadband source such as a super-luminescent diode (SLD), alternatively it may be a sweeping narrowband source (not shown).
  • SLD super-luminescent diode
  • the diode is coupled to a first length 20 of optical fibre and the first length of optical fibre is connected to a first input 22 of optical energy separating means, such as a circulator 24 .
  • a second port 26 of the circulator is connected via fibre 28 to a first lens 30 of an optical energy transmission system 32 .
  • An output 34 of the circulator is connectable to a known optical spectrum analyzer 36 .
  • the system further comprises a transducer 38 mounted on the shaft and which transducer in use modulates optical energy received from the source in accordance with changes in the variable to be monitored.
  • the transducer comprises a second length 40 of optical fibre and two elongate frequency sensitive optical reflector elements connected in the fibre.
  • the two elements may comprise a first Bragg grating 42 having a first center wavelength and a second Bragg grating 44 having a second and different center wavelength.
  • the gratings are mounted spaced from one another at a right angle relative to one another, and each at an angle of about 45 degrees relative to the longitudinal axis 14 of the shaft 12 .
  • the second length of fibre 40 is connected at one end thereof to a second lens 46 of the aforementioned transmission system 32 .
  • the transmission system 32 transmits optical energy through free space 48 between the platform 18 and the rotating member 12 as will hereinafter be described.
  • Second lens 46 is centrally mounted in a circular disc 50 mounted at one end of a tube 52 .
  • a ball bearing arrangement 54 comprising a stationary inner ring 56 and a rotary outer ring 58 separated by balls 60 in known manner.
  • First lens 30 is centrally mounted in the inner ring 56 to be substantially axially in line with the second lens 46 .
  • a flexible bellows member 62 is provided drivingly to connect the tube 52 to the shaft 12 .
  • Optical energy propagates from source 16 in a first direction via circulator 24 , lens 30 , free space 48 , lens 46 and optical fibre 40 .
  • Light of a first wavelength is reflected by grating 42 to propagate in the opposite direction.
  • Light of a second wavelength is similarly reflected by grating 44 .
  • the values of the wavelengths are proportional to the strain in the shaft.
  • the reflected energy is separated from the energy propagating in the first direction by the circulator 24 .
  • the reflected energy is directed to the analyzer 36 .
  • a typical diagram of reflected energy against wavelength obtained from analyzer 36 is shown at 64 in FIG. 3 .
  • Energy reflected by grating 42 is shown at 66 in FIG. 3 and energy reflected by grating 44 is shown at 68 .
  • FIG. 4 there is shown a diagram corresponding to the diagram in FIG. 3 , but for three different values of torque applied to the shaft.
  • a first diagram for no torque applied to the shaft has a first difference 70 is shown at 72 .
  • torque of 40 Nm applied to the shaft the difference between the wavelengths changes to a value 76 and for torque of 95 Nm, the difference increases to a value 78 .
  • FIG. 5 there is illustrated with squares measured values in wavelength difference against applied torque for comparison with theoretically computed values which are shown with a straight solid line.
  • the differential mode shift in wavelength between the reflected signals is proportional to the torsion and that a common mode shift, that is a change in the mean value of the wavelengths is proportional to the temperature of the gratings and hence the shaft or a region about the shaft. Because the measurement system and method enable one to separate strain and temperature effects, it is possible to compensate for temperature variations.
  • amplitude modulation introduced to the signals by slight misalignment of the lenses 30 and 46 carries information regarding speed of rotation of the rotating shaft.
  • optical sensors measure primarily strain and temperature
  • other configurations of the sensors it would be possible to do simultaneous measurements of temperature, bending moment changes, torsion and rotational speed.
  • the gratings 42 and 44 are located in substantially the same location on the shaft 12 in partially overlapping relationship.
  • This configuration enables measurement of time dependent or rotational angle dependent bending moment.
  • a common mode signal relating to the temperature at the shaft 12 which would normally change relatively slowly, could be separated from the signal relating to time dependent bending moment by a suitable low pass or band pass filter connected after detection of the optical signals.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
  • Optical Communication System (AREA)
  • Mounting And Adjusting Of Optical Elements (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)
  • Gyroscopes (AREA)
US10/551,060 2003-04-02 2003-12-05 Optical system and method for monitoring variable in rotating member Abandoned US20080011943A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ZA2003/2585 2003-04-02
ZA200302585 2003-04-02
PCT/ZA2003/000181 WO2004088884A1 (en) 2003-04-02 2003-12-05 Optical system and method for monitoring variable in rotating member

Publications (1)

Publication Number Publication Date
US20080011943A1 true US20080011943A1 (en) 2008-01-17

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US10/551,060 Abandoned US20080011943A1 (en) 2003-04-02 2003-12-05 Optical system and method for monitoring variable in rotating member

Country Status (7)

Country Link
US (1) US20080011943A1 (de)
EP (1) EP1614240B1 (de)
AT (1) ATE338394T1 (de)
AU (1) AU2003291221A1 (de)
DE (1) DE60308068T2 (de)
WO (1) WO2004088884A1 (de)
ZA (1) ZA200507969B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110051123A1 (en) * 2009-09-03 2011-03-03 Honda Motor Co., Ltd. Optical fiber sensor, pressure sensor, end effector and sensor signal processor
US20120162634A1 (en) * 2009-07-22 2012-06-28 Continental Teves Ag & Co. Ohg Speed sensor
WO2014012173A1 (en) * 2012-07-20 2014-01-23 Advanced Test And Automation Inc. System and method for measuring torque
WO2018063784A1 (en) 2016-09-27 2018-04-05 Illumina, Inc. Imprinted substrates

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3962911A (en) * 1974-11-21 1976-06-15 Beloit Corporation Method and apparatus for coupling signals from a rotating device with end shafts exposed
US4672214A (en) * 1984-07-06 1987-06-09 Honda Giken Kogyo Kabushiki Kaisha Optical switch having light source and receiver positioned stationary relative to steering wheel
US4746791A (en) * 1985-11-28 1988-05-24 Daimler-Benz Aktiengesellschaft Fiber optic sensor with an optical modulator having a permanent magnet for the detection of the movement or position of a magnetic component
US4767175A (en) * 1985-07-26 1988-08-30 Emil Wohlhaupter & Co. Rotary device for transmitting light signals including annular photoelectric transducers
US5182953A (en) * 1990-07-13 1993-02-02 Simmonds Precision Products, Inc. Method and apparatus for shaft torque measurement with temperature compensation
US6876786B2 (en) * 2002-10-02 2005-04-05 Cicese-Centro De Investigation Fiber-optic sensing system for distributed detection and localization of alarm conditions
US6876785B1 (en) * 1999-06-30 2005-04-05 The Board Of Trustees Of The Leland Stanford Junior University Embedded sensor, method for producing, and temperature/strain fiber optic sensing system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3962911A (en) * 1974-11-21 1976-06-15 Beloit Corporation Method and apparatus for coupling signals from a rotating device with end shafts exposed
US4672214A (en) * 1984-07-06 1987-06-09 Honda Giken Kogyo Kabushiki Kaisha Optical switch having light source and receiver positioned stationary relative to steering wheel
US4767175A (en) * 1985-07-26 1988-08-30 Emil Wohlhaupter & Co. Rotary device for transmitting light signals including annular photoelectric transducers
US4746791A (en) * 1985-11-28 1988-05-24 Daimler-Benz Aktiengesellschaft Fiber optic sensor with an optical modulator having a permanent magnet for the detection of the movement or position of a magnetic component
US5182953A (en) * 1990-07-13 1993-02-02 Simmonds Precision Products, Inc. Method and apparatus for shaft torque measurement with temperature compensation
US6876785B1 (en) * 1999-06-30 2005-04-05 The Board Of Trustees Of The Leland Stanford Junior University Embedded sensor, method for producing, and temperature/strain fiber optic sensing system
US6876786B2 (en) * 2002-10-02 2005-04-05 Cicese-Centro De Investigation Fiber-optic sensing system for distributed detection and localization of alarm conditions

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120162634A1 (en) * 2009-07-22 2012-06-28 Continental Teves Ag & Co. Ohg Speed sensor
US20110051123A1 (en) * 2009-09-03 2011-03-03 Honda Motor Co., Ltd. Optical fiber sensor, pressure sensor, end effector and sensor signal processor
US8547534B2 (en) * 2009-09-03 2013-10-01 Honda Motor Co., Ltd. Optical fiber sensor, pressure sensor, end effector and sensor signal processor
WO2014012173A1 (en) * 2012-07-20 2014-01-23 Advanced Test And Automation Inc. System and method for measuring torque
EP2875326A4 (de) * 2012-07-20 2016-03-30 Advanced Test And Automation Inc System und verfahren zur drehmomentmessung
WO2018063784A1 (en) 2016-09-27 2018-04-05 Illumina, Inc. Imprinted substrates

Also Published As

Publication number Publication date
DE60308068T2 (de) 2007-03-15
AU2003291221A1 (en) 2004-10-25
WO2004088884A1 (en) 2004-10-14
ATE338394T1 (de) 2006-09-15
ZA200507969B (en) 2007-02-28
EP1614240B1 (de) 2006-08-30
DE60308068D1 (de) 2006-10-12
EP1614240A1 (de) 2006-01-11

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Owner name: UNIVERSITY OF JOHANNESBURG, SOUTH AFRICA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SWART, PIETER LODEWIKUS;KRUGER, LUDI;CHTCHERBAKOV, ANATOLI ALEKSANDROVICH;AND OTHERS;REEL/FRAME:017722/0663;SIGNING DATES FROM 20060505 TO 20060509

STCB Information on status: application discontinuation

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